1. Technical Field
The present disclosure relates to a vehicular illumination lamp which is equipped with a projection lens.
2. Related Art
As described in JP-A-2006-127819 and JP-A-2009-43543, it is known it have vehicular illumination lamps that are configured in such a manner that light emitted from a prescribed point on the axial line extending in the lamp front-rear direction is output forward as light that is parallel with the axial line by a projection lens that is located in front of a light source.
The projection lens of a vehicular illumination lamp described in JP-A-2006-127819 is a planoconvex lens with a convex front surface.
On the other hand, the projection lens of a vehicular illumination lamp described in JP-A-2009-43543 is configured in such a manner that plural lens pieces having the same shape which are fan-shaped portions having a prescribed central angle cut out of an ellipsoidal lens whose front surface is a convex, ellipsoidal surface are connected to each other in the circumferential direction.
Whereas the front surface of the projection lens described in JP-A-2006-127819 has a circular perimeter shape, the following problem arises if it is attempted to give the perimeter of its front surface a non-circular shape to increase the degree of freedom of lamp designing.
In the projection lens described in JP-A-2006-127819, if it is attempted to give the perimeter of its front surface an shape that is close to a rectangle when viewed from the front side of the lamp as in a front surface 2a of a projection lens 2 shown in FIG. 14A, the projection lens is chamfered at four locations in the perimeter. In the case of the projection lens 2, new end surfaces 2b are formed so as to extend rearward from four peripheral positions of the front surface 2a. However, a problem arises that if light emitted from a light source reaches and exits from the end surfaces 2b. This light becomes stray light that is not controlled as lamp illumination light.
To prevent occurrence of such stray light, as shown in FIG. 14B, it is necessary to cover the end surfaces 2b with a lens holder 4. However, in this case, the front end surface 4a of the lens holder 4 is formed with projections 4a1 at plural positions, whereby the appearance of the lamp is impaired.
On the other hand, in the projection lens described in JP-A-2009-43543, even if the perimeter of its front surface is given a non-circular shape, end surfaces that are formed in the perimeter can be made so small that almost no stray light is produced. However, in this projection lens, ridge lines are formed in the front surface at the connecting portions between the fan-shaped lens pieces. This impairs the appearance of the lamp.